Insert having removable liner



,.-Seplh 23, 1969 R, NEuscHo-rz 3,468,358

INSERT HAVING REMovABLE LINER Filed Aug. 28. 1967 s4 le le se 23 536 ,59 Qa ,3

I N VENTOR.

rroenfy 1208527' Niuscnorz lUnited States Patent O U.S. Cl. 151-8 8 Claims ABSTRACT OF THE DISCLOSURE A threaded insert assembly having an externally threaded outer sleeve and an internally threaded liner, with the sleeve and liner having engaging threads, and being retained against separation by a key extending axially within opposed grooves in the sleeve and liner. The key is formed of an elongated element doubled back to a U-shaped conliguration having a radially inner leg which is straight and a radially outer leg with a rst straight portion and a radially outwardly iiared end. The key is removed from the grooves `by a tool which engages the extremity of the radially inner straight leg of the key, and which extends into and is located by a slit formed in the sleeve in communication with the grooves.

Background of the invention This invention relates to insert assemblies to be screwed into a carrier part, and adapted to receive and engage a coacting screw in a relation connecting the screw to the carrier part through the medium of the insert.

Insert assemblies have been proposed in the past which have included two separable parts, one of which is an outer generally tubular sleeve, and the other of which is an inner generally tubular liner adapted to be removed from the sleeve and replaced or reversed after wear. The liner in such devices threadedly engages the interior of the sleeve, and is retained against separation by a key which is inserted axially into a pair of opposed grooves or keyways in the sleeve and liner. To remove the sleeve, it is necessary to pull the key outwardly from the grooves, following which the sleeve is free to be unscrewed and replaced. However, the pulling of a key of the previously proposed type has entailed a more complicated type of manipulation than would be desired, and specifically has required at least two different pulling steps or operations before the key is completely out of the grooves.

Summary of the invention An insert device embodying the present invention is of the above discussed general type, but utilizes a key which is much more readily removable from its position of locking engagement with the sleeve and liner, to thus free the liner more readily for removal from the sleeve. As will appear, a key constructed in accordance with the invention can be pulled from its locking position to a completely withdrawn position by a single removal step, that is, by a single pulling operation performed on the key by a tool which engages its inner end. Further, the present assembly is in certain respects especially useful for situations in which the device is to be connected into a blind hole, in which the carrier structure may have an inner wall received in close proximity to the inner end of the insert in a relation which might interfere with removal of the keys in Some prior devices of this general type. It is contemplated that the present devices may for example be utilized very eHectively in honeycomb structures, in which one of the skins but not the other may be cut away at the location of the insert assembly.

Structurally, the key employed in an insert assembly ice embodying this invention is formed of an elongated piece of material which is doubled back at it axially outer end to form an element which, as viewed in axial section, is of generally U-shaped conliguration, and which thus has two axially inwardly projecting legs. A radially inner one of these legs is straight along substantially its entire axial extent, while the radially outer leg has a rst straight portion and then flares radially outwardly at its axially inner end. This Haring portion projects axially beyond the extremity of the straight radially inner leg, and acts to prevent unwanted axially outward separation of the key from the connected parts.

A removal tool is engageable with the axially inner end of the straight leg of the key, and can pull the key from the insert assembly by a single stroke of the tool. Further, the tool, during its pulling action, is at least partially received within an axially extending slit formed in the side wall of the liner, which slit communicates with the grooves, with reception of the tool in the slit serving both to locate the tool properly relative to the key for the pulling action, and also to enable movement of the key engaging portion of the tool axially outwardly through the slit during the pulling action.

Brief description of the drawing The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawing, in which:

FIG. l is an axial section through an insert assembly constructed in accordance with the invention, and shown in its installed position within a honeycomb structure;

FIG. 2 is a side elevational view of the FIG. 1 assembly;

FIG. 2 is an enlarged axially inner end View taken on line 3-3 of FIG. 2;

FIG. 4 is a partly elevational and partly axial sectional View showing the manner in which a pulling tool can engage and remove the key; and

FIG. 5 is an inner end View taken on line 5--5 of FIG. 4.

Description of the preferred embodiment Referring first to FIG. 1, I have shown at 10 an insert assembly constructed in accordance with the invention as it appears after installation within a honeycomb structure 11 of the well known type now widely used in forming walls of aircraft and other products. The honeycomb structure 11 has two typically parallel sheet metal skins 12 and 13 which are separated and interconnected by the honeycomb core 14 consisting of a large number of thin interconnected walls of metal foil or thin sheet metal suitably welded or otherwise secured together in a conventional honeycomb pattern, and welded or otherwise secured at their ends 15 to the desirably metal skins 12 and 13.

In order to provide for anchoring of the insert assembly 10 within the honeycomb structure 11, the core material 14 has been cut away within a circular area centered about the axis 16 which is to be the axis of the installed insert assembly, and a circular opening 17 also centered about axis 16 has been cut in one of the skins 12. Also, a mass of resinous plastic material 18 has been iilled into the cavity left between the skins at the location at which the core material 14 has been cut away; and after the material 18 has polymerized to a hardened condition, it has been drilled out to form a cylindrical bore or passage 19 within the plastic material and centered about axis 16. Preferably, the opening 17 has been so formed as to provide an annular aring countersink surface 20 in skin 12 and centered about axis 16, with the resinous plastic material typically forming a continuation of this countersink surface at 21.

The insert assembly includes an outer essentially tubular sleeve 22 and an inner essentially tubular liner 23, releasably retained against relative rotation by a locking key 39. Sleeve 22 has external threads formed on its outer surface at 25, which threads are desirably of a self locking and self tapping type, and for best results are of the type disclosed and claimed in my United States Patent No. 3,200,691. More specifically, these threads 25 preferably have the alternately peaked and recessed peripheral shape illustrated in FIG. 3. This shape is given to the threads by forming sleeve 22 from bar stock having this peaked and recessed cross section, that is, having alternate outwardly convex peaks 26v and intermediate recesses 27 at circularly spaced locations about the periphery of the stock. This stock is threaded externally to form the threads 25 which are of uniform cross section along their entire helical extent, except insofar as the threads are truncated by the outer peaked and recessed surface of the stock, so that the threads have radially outer surfaces 28 following this waving peaked and recessed shape of the original stock. The threads desirably have a profile which is sharper than the conventional 60 degree profile, and which for best results defines an angle a of about 40 degrees, rather than 60 degrees, between the opposite side faces 29 of each turn of the thread. Axially between the successive turns of the thread, the outer surface of sleeve 22 has a straight cylindrical modified minor diameter surface 30, which is considerably longer axially thran the minor diameter surface of a standard thread.

At its axially outer or upper end, the tubular sleeve 22 forms an annular fiaring flange 31, which desirably has external and internal parallel annular surfaces 32 and 33 fiaring essentially in correspondence -with the angularity of countersink surface of the honeycomb structure. This fiange 31 may initially be formed as a directly axially projecting end portion of the sleeve 22, at a diameter small enough that the flange will not have the external configuration of the peaked and recessed stock, but with that end portion of the sleeve then being spun or otherwise deformed annularly outwardly to the FIG. l position after formation of threads 25. At the axially inner end yof threads 25, there may be provided on the radially outer side of the sleeve a downwardly or axially inwardly tapering chamfer surface 34, which partially and gradually truncates the lower turn or turns of threads so that they progressively decrease in maximum diameter as they advance downwardly at the end of the sleeve.

Internally, sleeve 22 has threads 35 which engage external threads 36 on liner 23 in a relation enabling the liner to be screwed axially into the sleeve. Within the liner itself, there are formed additional threads 37 into which a coacting screw may be connected. Threads 37 are desirably finer than external threads 25, while the threads and 36 between the liner and sleeve may be of the cross section illustrated in FIG. 1, and be coarser than threads 37, and preferably also threads 25. As will be apparent, all of the various described sets of threads are for best results centered about the common axis 16 of the device. At the axially inner end of sleeve 22, this part may contain an annular downwardly fiaring frustoconical internal surface 38, also centered about axis 16.

The external surface of liner 23 contains a groove 139 which extends axially along the outer surface of the liner and extends through and interrupts the external threads 36 of the liner. As seen best in FIG. 3, this groove is defined by a radially inner axially extending wall surface 40, which is disposed parallel to main axis 16 of the device, and which lies in a plane disposed perpendicular to a radius 140 leading outwardly from the axis. Surface 40 is interrupted centrally by an axial slit 42 which extends through the side wall of the liner to place groove 139 in communication with the interior of the liner. This slit is continuous along the entire length of the liner, and has its opposite sides defined by two parallel planar spaced side wall surfaces 43 which extend axially and are parallel to and spaced equal distances from the previously mentioned radius 140. The opposite sides of groove 139 form parallel spaced opposite side surfaces 41, which may be planar and extend axially and spaced equal distances from radius 140.

The inner wall surface of sleeve 22 forms a second groove 44 which is complementary to the opposed groove 139 in the liner, and which more specifically is defined at its radially outer side by a planar axially extending groove wall surface 45 disposed parallel to wall 40 of groove 139, and perpendicular to the mentioned radius 140. This surface 45 extends between two spaced opposite side wall surfaces 46 which are planar and extend axially and are aligned with and form continuations of side wall surfaces 41 of groove 139. Thus, the two grooves 139 and 44 form together an axially extending key receiving passageway having the rectangular transverse cross section illustrated in F IG. 3.

The key 39 is formed of an elongated strip of sheet metal or other fiat material which is doubled back at its upper or axially outer end 47 to form a removable locking key of generally U-shaped configuration, for reception within the two opposed grooves 139 and 44. Thus, the key forms two legs 48 and 49 extending downwardly from the upper return bend location 47. The entire key, including both of its legs, is of a width w (FIG. 3) slightly smaller than the width dimension between the two opposite side surfaces 41 or 46 of the grooves, so that the key is readily receivable within those grooves in locking relation. At their opposite sides, the two legs have axially extending planar surfaces at 5t) lying within two spaced parallel planes 51 extending parallel to and offset equidistantly in opposite directions from axis 16.

The strip of material from which key 39 is formed is of uniform radial thickness t (FIG. l) along its entire length. The inner leg 48 of the key is straight along its entire axial length, from upper return bend location 47 to a lower or axially inner end surface 52 of leg 48 disposed transversely of axis 16. This surface 52 is preferably planar, and aligned transversely of axis 16 with the lower or axially inner end surface 53 of liner 23. The

radially inner surface 54 of leg 48 of the key may be planar, and engages the inner wall surface 40 of groove 139, at opposite sides of the slit 42. The radially outer surface 55 of key leg 48 is parallel to inner surface 54, and like that surface is disposed parallel to axis 16, and lies in a plane disposed perpendicular to radius of FIG. 3.

The radially outer leg 49 of key 39, in advancing downwardly from the upper return bend portion 47 of the key, has a first elongated straight axial portion 56 extending parallel to and contacting inner leg 48, and continuing to a location 57 near the lower end of the key at which the lower extremity of leg 49 fiares or advances progressively radially outwardly as indicated at 58 to the location of a bottom edge 159 of leg 49. Portion 58 of leg 49 fiares at an angle 38 within the lower portion of sleeve 22, so that the radially outer surface of the key portion 58 engages the surface 38 at 59, in a relation resisting upward withdrawing movement of the key from the grooves. The inner planar surface 60 of leg 49 engages outer surface 55 of leg 48 between the location 61 and location 57, and the planar radially outer surface 149 of `the straight axial portion of leg 49 engages the radially inwardly facing surface 45 of groove 44 in the sleeve. It is noted that the lower edge 159 of radially outer leg 49 of the key is preferably located downwardly or axially inwardly beyond the lower edge 52 of inner leg 48, and for best results is aligned essentially with the bottom end of sleeve 22.

For removing key 39 from the insert assembly, I provide an elongated tool represented at 63 in FIGS. 4 and 5. rIhis tool is a rigid typically metal part, having an upper handle portion 64 by which it is manipulated during a pulling operation, and which carries a key engaging end 65 adapted to be inserted downwardly into the interior of liner 23 (FIGS. 4 and 5). As seen best in FIG. 5, the portion 65 of the tool which is insertible into the liner is essentially at, .and of a thickness a' corresponding approximately to the width of slit 42 (FIG. 3) between the opposite side wall surfaces 43 of that slit. Thus, the portion 65 of the tool is insertible into the slit in a position locating and guiding the tool With respect to liner 23 and key 39. At its lower extremity, portion 65 of the tool has a hook like projection 66 (FIG. 4) having a radial extent corresponding to the radial thickness of inner leg 48 of the key, and having a key engaging surface 67 disposed transversely of axis 16 and adapted to contact the inner edge 52 of the key in pulling relation. In extending upwardly above lug 66, the portion 65 of the tool has an axially extending planar surface 67 engageable with the radially inner surface 54 of key leg 48, and of an axial length slightly greater than the length of leg 48 to enable the tool to be received in the position illustrated in FIG. 4. The opposite edge 68 of the tool may extend parallel to surface 67, and is so positioned as to be received within the minor diameter portions of the adjacent threads 37 when lug 66 is moved leftwardly in FIG. 4 far enough to avoid contact with the key, to thus enable insertion of the tool downwardly into the insert assembly. The opposite side surfaces 69 of portion 65 of the key are parallel t-o one another and planar, and parallel to axis 16 in the FIG. 4 position of the tool, and are perpendicular to the surfaces 67 and 68 of FIG. 4.

In using the described insert assembly, a honeycomb structure may first be prepared to the condition of the structure illustrated at 11 in FIG. 1, following which the entire insert assembly consisting of sleeve 22, liner 23 and key 39, is screwed into the plastic material 18. As the outer sleeve 22 is advanced downwardly and rotated withlin the initially unthreaded straight cylindrical bore 19 in the plastic material, the peaked and recessed external threads 25 of the sleeve act to progressively form mating internal threads 125 in the plastic material by a highly effective thread rolling action. Further, after the insert assembly has reached the FIG. 1 position, the peaks 28 of threads 25 coact with the internal threads 125 in the resinous plastic material in a manner attaining a self locking action, resisting and preventing unscrewing rotation of the sleeve 22 from the honeycomb assembly. Upper flaring flange 31 is received either in engagement with countersink surface 20 of upper skin 12, or else in very closely spaced relation thereto, so that the flange can contact that countersink in use in a manner preventing any more than a very slight displacement of sleeve 22 relative to the honeycomb structure. After complete installation of the assembly 10, a screw or stud may be advanced into engagement with threads 37 of liner 23, to thus connect the screw or its equivalent to the honeycomb structure through the medium of the insert assembly.

It liner 23 becomes worn from use, it may be easily replaced or reversed, by merely removing key 39. This is effected by inserting the tool 63 of FIG. 4 downwardly through the interior of the liner and then laterally far enough to move lug 66 to a position of engagement with the inner end edge 52 of radially inner leg 48 of the key (the FIG. 4 position), with surface 67 of the tool engaging surface 54 of the key, so that the edge of the key is received and confined and located within slit 42 formed in the side wall of the liner. This intertting relationship of the axially extending edge portion of the tool with slit 42 locates the tool accurately so that lug 66 can be easily and eiectively engaged with the end edge of the key. With the parts in the FIG. 4 relation, the tool 63 is pulled upwardly by manipulation of its handle portion 64, and through a vertical stroke long enough to withdraw the entire key upwardly or axially outwardly from both of the grooves 139 and 44 of the liner and sleeve. As the key is pulled upwardly, the forces exerted against the key act to cause surface 38 of the outer sleeve (FIG. l) to progressively cam or deliect portion 58 of the key radially inwardly to a position of axial alignment with the straight axial portion 56 of outer leg 49 of the key, so that portion 58 may follow the rest of the key upwardly or axially outwardly through the grooves. During this entire upward pulling stroke of tool 63, the tool remains in its FIG. 4 position of engagement with the key, and remains within slit 42 in the side wall of the liner, to thus continuously be located and guided by that slit, and maintained in proper intertting engagement with the key.

After the key has been removed, the liner 23 may be unscrewed from sleeve 22, and then be replaced by another liner, or be reversed axially and then be screwed back into the position of FIG. l relative to the sleeve 22. Key 39 can then be forced downwardly within grooves 139 and 44, after iirst deiiecting portion 58 of the key radially inwardly to its straight axially extending condition; and when the key reaches the FIG. 1 position, portion 58 will return radially outwardly into engagement with surface 38 to hold the key in position.

In order to function in the desired manner, key 39 should be formed of a resiliently deformable spring material, tending to normally assume the condition of FIG. l, but enabling inward deilection of portion 58 of the key to be discussed straight axially extending condition without exceeding the elastic limit of the material. In the FIG. l condition, portion 58 retains the key against accidental axially outward removal from the grooves, while the inner skin 13 of the honeycomb structure is received in close enough proximity to inner edge 159 of the outer leg of the key to prevent the key from moving accidentally out of the grooves in the opposite direction, that is, axially inwardly or downwardly in FIG. 1. Thus, the key is effectively retained in position and yet is easily removed by the tool 63 in a single withdrawing operation.

I claim:

1. An insert assembly comprising an outer generally tubular sleeve having external threads to be screwed into a recess in a carrier structure and also having internal threads, a generally tubular removable liner Within said sleeve having external threads to be screwed into said internal threads in said sleeve, and liner having internal threads into which a coacting screw may be connected to secure said screw to the carrier structure through said insert assembly, said sleeve containing a groove in its radially inner surface extending axially through and interrupting and internal threads in the sleeve, said liner containing a groove in its radially outer surface extending axially through and interrupting said external threads on the liner and located radially opposite said groove in the sleeve, and an axially extending `key removably received in said two grooves in a relation locking the liner against uncrewing rotation relative to the sleeve, said key comprising an elongated strip of material doubled back to a U-shaped form having a return bend at its axially outer end and having a radially inner leg and a radially outer leg extending axially inwardly from said return bend within said grooves, said radially inner leg, as viewed in axial section, being substantially straight along its entire axial length and having an end edge facing axially inwardly at its axially inner end and engageable by a tool to pull the key axially outwardy lfrom the grooves, said radially outer leg in extending axially in- Wardly from said return bend Ihaving a rst relatively long portion which is substantially straight and extends substantially directly axially and is substantially parallel to said radially inner leg and substantially directly adjacent it along essentially the entire length of said irst portion, and then having a shorter axially inner end portion which flares radially outwardly relative to and away from said inner leg and to a position =farther radially outwardly than said straight first portion of said outer leg, the entire length of said outer leg, including both of said portions thereof, -being located farther radially outwardly than any portion of said inner leg, said outer sleeve having a shoulder surface against which said axially inner end portion of said radially outer leg is engageable axially outwardly in a relation retaining said key against accidental axially outward removal from the grooves, said inner end portion of the outer leg being dellectible radially inwardly by said shoulder surface when the key is forced axially outwardly by said tool, said liner having an axially extending slit extending through its side wall at a location opposite and communicating with said grooves but narrower than said groove in the liner and through which said tool is engageable, from within the liner, with said end edge of said radially inner leg to pull the Ikey from the grooves.

2. An insert assembly as recited in claim 1, in which said shoulder surface flares progressively radially outwardly as it advances axially inwardly.

3. An insert assembly as recited in claim 1, in which said shoulder surface ares progressively radially outwardly as it advances axially inwardly and essentially in correspondence with and parallel to the flare of said end portion of the radially outer leg.

4. An insert assembly as recited in claim 1, in which said external threads on said sleeve are on self tapping and self locking coniiguration.

5. An insert assembly as recited in claim 1, in which said sleeve has an essentially annular ange at its axially outer end ilaring progressively radially outwardly as it advances axially outwardly.

6. An insert assembly as recited in claim 1, in which said outer leg projects axially inwardly beyond said end edge of the inner leg.

7. An insert assembly as recited in claim 1, in which said llaring inner end portion of the outer leg projects axially inwardly beyond said end edge ofthe inner leg, and flares continuously from a location axially outwardly of said end edge of the inner leg to a location axially inwardly of said end edge of the inner leg to a location axially inwardly beyond said end edge.

8. An insert assembly as recited in claim 1, in which said flaring inner end portion of the outer leg projects axially inwardly beyond said end edge of the inner leg, and flares continuously from a location axially outwardly of said end edge of the inner leg to a location axially inwardly beyond said end edge, said shoulder surface daring progressively `radially outwardly as it advances axially inwardly and daring essentially in correspondence with and parallel to the flare of said end portion of the radially outer leg, in essential engagement therewith.

References Cited UNITED STATES PATENTS 329,861 lll/'1885 Stark 85-8.3 2,397,325 3/1946 Newcomb 85-8.3 2,444,145 6/ 1948 Rosan ISI-41.73 2,549,459 4/1951 Guest 85-8.3 2,639,179 `5/1953 Phelps ISI-41.73 2,742,938 4/1956 Neuschotz ISI-41.73 3,054,436 9/1962 Rosan ISI-41.73 3,163,197 l2/l964 Rosan et al ISI- 41.73 3,200,691 1965 Neuschotz --47 MARION PARSON, JR., Primary Examiner US. Cl. X.R.

29-247; 85-831. l5l-4l.73 

